Not Applicable
Not Applicable
Not Applicable
The present invention relates in general to electrical/electronic weighing systems and more particularly to portable weigh scales incorporating strain gauge load cells used on forklift trucks and the like.
There are a number of related patented weighing systems that to varying degrees of effectiveness, enable forklift trucks and the like to perform weighing functions in addition to typical lifting and transporting functions. However, with regard to aspects such as portability, accurately weighing certain load types, lifting functions, manufacturing costs, installation, removal and servicing, these prior art systems can encounter specific problems.
Some of these system designs are not based on or suited for being fitted to standard lift truck forks and therefore tend to require more custom manufactured components and complexity as evident in U.S. Patent to Boubille, U.S. Pat. No. 4,899,840 and Balduin et al., U.S. Pat. No. 4,638,876. The use of custom manufactured components and increased design complexity usually result in higher manufacturing costs and requiring more highly skilled or knowledgeable service personnel.
Some of these system designs require structural modifications or additional attachments to the lift truck carriage assembly, adding cost and resulting in more difficult and time consuming installation and removal as evident in U.S. Patent to Johnson et al., U.S. Pat. No. 6,002,090. Further, the addition of weigh system components such as a secondary carriage can potentially obscure operator vision of the load and create a potentially unbalanced and unsafe condition because the position of the lift forks is moved forward relative to the lift truck resulting in incorrect load centers as specified by the lift truck manufacturer.
Some of these system designs are limited with regard to ease of performing weighing functions in that they must be activated into the lift mode before weighing functions can be performed as evident in U.S. Patent to Zefira, U.S. Pat. No. 5,739,478. The weight of the load cannot be measured by just placing the load on the lifting surface of the weigh system. Further, because weighing functions cannot be performed with the lifting surface in the fully lowered position, it is difficult or impossible to safely check the load weight relative to the maximum lifting capacity of the lift truck or the like before attempting to lift the load.
Some of these systems do not utilize the entire lifting surface for weighing, making the specific placement of certain loads more critical for this purpose as evident in U.S. Pat. to Russo, U.S. Patent No. 4,420,053.
Some of these systems employ mechanically elaborate designs, more likely to be prone to mechanical malfunction and entail higher manufacturing cost to address weight measurement accuracy problems resulting from eccentric loads as evident in U.S. Patent to Balduin et al., U.S. Pat. No. 4,638,876.
Some of these systems have irregular or stepped lifting surfaces that could cause binding while attempting to slide the weighing system under a standard pallet or the like as evident in U.S. Patent to Boubille, U.S. Pat. No. 4,899,840.
Electronic weigh systems fitted to forklift trucks and the like tend to be bulky and heavy assemblies that are either integral with the equipment they are used on, or affixed to such equipment in a way that makes portability, ease of installation and removal of such systems difficult. Further, it is also difficult to optimize the lifting, transport and weighing functionality of lift truck equipment and the like for a wider range of load types with just one weigh scale design configuration. For instance, to optimize the weighing accuracy for a load such as a flat sheet steel coil, that is cylindrical in shape, the weight of the coil must be centered as close as possible over the load sensing cells. The typical relative position of contact points between the inside diameter of such a load and prior art forklift weigh sensing scales prevent such centering.
A cost effective portable weigh scale system comprised of various preferred interchangeable design configuration options that can be easily serviced, fitted to and removed from the standard lift forks of lift truck vehicles or the like increasing the functional range of such vehicles without requiring their modification. Each design configuration of the said weigh scale system is generally constructed of standard metal tubing sections, a fabricated metal attachment and load sensing cells that are affixed together with fasteners fitted through spacers. When a load is placed or fitted onto the top surfaces of the said weigh scale system, the load sensing cells elastically flex, transmitting load weight readings through a wiring system to a commercial display mounted suitably near the operator.
It is an object of the present invention to provide a versatile, low to high weighing capacity, portable, compact and lighter weight weigh scale system with easily interchangeable design configuration options better suited to the lifting and accurate weighing of a wider range of load types. This includes cylindrical loads such as flat sheet steel coil, in addition to lifting, weighing and transport functions in more general applications.
It is another object of the present invention that it can be fitted to standard lift truck forks without modification to the lift truck or its forks.
It is a further object of the present invention that it""s assembly with and removal from lift truck forks be easy, facilitating quick conversion between cylindrical load and standard applications with the same lift truck forks.
A feature of the present invention is that it can be fitted onto standard lift truck forks without the need for modifications to the lift truck or its forks.
Another feature of the present invention is that it is primarily constructed from standard tubing sections, simple sheet metal forms and load sensing cells to form an assembly that minimizes the requirement for extensive custom manufacturing and therefore maximizes cost savings.
Another feature of the present invention is that its compact size, lighter weight construction, simple slide on/off design for standard lift truck forks and the elimination of required modifications to the lift truck and its forks, facilitates ease of installation and removal as well as portability of this design.
Another feature of the present invention is that because of its design simplicity and ability to be easily fitted onto and removed from standard lift truck forks, servicing by technicians without highly specialized knowledge and skills is facilitated. Further, this design simplicity facilitates the convenience of servicing onsite, saving the additional time and money required for servicing offsite by specialists.
Another feature of the present invention is that load sensing cell overload protection is accomplished by means of simple load sensing cell, weigh scale assembly component and lift fork proximity arrangements. By limiting load sensing cell movement and direct exposure to external objects, these arrangements limit load cell flexure to within its operable limits and prevent possible load sensing cell damage from high impact.
Another feature of the present invention is that additional attachment components such as a secondary carriage for mounting the forks to the lift truck are not required. Therefore the position of the forks is kept safely at the distance from the lift truck specified by the manufacturer, thus maintaining proper balance between the forks and the truck for lifting, weighing and transporting functions. Further, operator vision of a load is not potentially obscured by said additional attachment components.
Another feature of the present invention is that it provides easily interchangeable design configuration options better suited to the lifting and accurate weighing of a wider range of load types including flat sheet steel coil, in addition to lifting, weighing and transport functions in more general applications.
Another feature of the present invention is that a weigh scale configuration can be selected to perform weighing functions with the lift forks in the fully lowered position. As a result, load weight can be safely checked relative to the maximum lifting capacity of the lift truck before attempting to lift the load, thus avoiding potential injury to the operator and damage to the lift truck.
Another feature of the present invention is that a low profile weigh scale configuration can be selected to allow easy access of the lift forks and weigh scale under standard pallets.
Another feature of the present invention is that the entire lifting top surface can be utilized for weighing.
Another feature of the present invention is that the load sensing cells are electronically matched to transmit accurate weight data regardless of the positioning of the load on the lift forks and weigh system assembly.
Another feature of the present invention is that its simple slide on/off assembly with standard lift truck forks, optional design configurations, compactness and lighter weight facilitate quick and easy conversion of standard lift truck forks for various uses. These uses can include use for general lifting and transport functions as well as use for accurately weighing a wider range of load types that can include cylindrical loads such as flat sheet steel coil. This feature thus expands the effective range of application of unmodified standard lift truck forks.
Another feature of the present invention is its implementation of auxiliary load sensing cells to reinforce the structural integrity of the design. Such reinforcement prevents potential convex and concave deformation in the center section of this weigh scale system while under load and augments the weighing capacity of the primary load sensing cells. This feature facilitates the higher weigh scale registration capacity required for heavier loads, and without overloading the primary load sensing cells or significantly increasing the bulk or cost of the system.
Another feature of the present invention is that the auxiliary load sensing cells are not affixed to the upper or top components of the weigh scale assembly. This eliminates weighing errors resulting from the potential binding action caused by utilizing more than two load sensing cells to sense load weight and transmit weight readings.
Another feature of the present invention is the implementation of a stretchable extension cable and end fittings that function as an inexpensive interconnect between the weigh sensing system and a digital weight readout display mounted appropriately near the operator. The stretchable extension cable enhances resistance to damage if it is inadvertently pulled. The simple, easy to use plug-in end fittings facilitate quick and easy no-tool connection and disconnection of the weigh scale system to and from the lift truck weight readout display for servicing or other lift truck functions.